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A175708
n-th semiprime minus n.
1
3, 4, 6, 6, 9, 9, 14, 14, 16, 16, 22, 22, 22, 24, 24, 30, 32, 33, 36, 37, 37, 40, 42, 45, 49, 51, 55, 57, 57, 57, 60, 61, 61, 61, 71, 75, 78, 80, 80, 81, 81, 81, 86, 89, 89, 95, 95, 95, 96, 96, 104, 106, 106, 107, 111, 113, 120, 120, 124, 125, 126, 132, 138, 138, 138, 139
OFFSET
1,1
FORMULA
a(n) = A001358(n) - A000027(n).
MATHEMATICA
Module[{nn=300, sps}, sps=Select[Range[nn], PrimeOmega[#]==2&]; #[[1]]-#[[2]]&/@Thread[ {sps, Range[Length[sps]]}]] (* Harvey P. Dale, Jun 12 2024 *)
CROSSREFS
Cf. A001358.
Sequence in context: A158907 A338281 A338723 * A373709 A023830 A063649
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected (61 replaced by 71) by R. J. Mathar, Aug 13 2010
STATUS
approved